1. Field of the Invention
The present invention relates to a system for photographing an object, and more particularly, to a method for controlling a camera with motion information of the object that is obtained during compression of input images.
2. Description of the Prior Art
Generally, digital photography systems use data compression techniques to reduce the volume of data, and thereby record a greater volume of image data during the shooting, facilitating transmission of the photographed information to a remote area. For example, a digital television transmission system compresses the image data obtained by the camera, and transmits the compressed image signals as broadcasting signals.
FIG. 1 is a flowchart showing the conventional image compression method for an image compression/recovery system. When the image information of the object photographed by the camera is input (step S11), the image compression/recovery system performs pre-processing of the input image (step S12). That is, signal processing is performed on the raw camera input to remove and prevent noise from the input images. Then, by comparing such processed images with the preceding frames, a motion vector of a macro block is calculated (step S13). Next, post-processing is performed to compress the input images (step S14). Digital encoding is performed (step S15), and finally compressed data of the input images is generated (step S16).
The ‘motion vector’ of the macro block, which is used to compress the image data, indicates a direction of an object moving among the image signals of the preceding and following frames. The motion vector is represented in two dimensions, i.e., in the horizontal and vertical directions. For example, if the motion vector of a particular macro block shows the values of (2, −3), it means the motion vector of the particular macro block has moved by two pixels in the horizontal direction, and by −3 pixels in the vertical direction.
Through the above-described compression of data, image data can be stored and transmitted to a remote area in greater volume and at a higher speed.
In certain applications, automatic tracking systems are advantageous. Automatic tracking systems are able to control a camera to track a moving object through signal processing of the input images.
FIG. 2 is a flowchart illustrating a conventional camera controlling process. When the image is input (step S21), the system performs pre-processing with respect to the input image (step S22). Next, the input image is divided into a plurality of areas (step S23). The plurality of areas is categorized into a background region and a motion region, so that the moving object is extracted (step S24). Then, the size and the motion information of the extracted moving object are obtained (step S25). Based on the size and motion information of the extracted moving object, pan/tilt and zoom-in/zoom-out of the camera is controlled (step S26). Through the above-described processes, the moving object is automatically tracked, and thus, the photographing is performed.
Typically, automatic tracking systems use image compression algorithms, such as those described above, to reduce storage and transmission requirements. Research is currently underway to develop an image compression algorithm that would enable the transmission of the moving object being tracked to a remote location using the internet or a wireless communication network.
However, in conventional automatic moving object tracking systems as described above, the process of compressing the input image and the process of tracking the moving object are performed independently of each other. Because the process of compressing the input image and the process of processing the input image for camera control are currently performed separately, control units are subjected to considerable overload and unnecessary power consumption.